Hi all, need help with car problem. Have 2001 Subaru Legacy GT Wagon (4 cyl 2.5 boxer engine, 5sp MT, no turbo). Have taken pristine care of this car, every scheduled maintenance and oil change per Subaru recommendations has been done. Currently has 118K miles. Last week developed slight roughness at idle and very low RPM. Engine wasn’t bucking or anything, but felt like a tiny rough shake every now and then. Didn’t notice any engine performance issues. Check engine light NOT on. Car sat for 2 days and then next day drove. This time engine roughness was just slightly more noticeable, but still almost undetectable. Again slight roughness at lower RPM’s, and seemed to lose slight power when engine would shake. Seemed to go away at higher RPMs (maybe over 1500 RPM). Later that night check engine light came on. This time it appeared roughness would occur at higher RPM’s (maybe up to 2K RPM) but roughness did not necessarily get worse in intensity.
Next day was driving on the highway and this time roughness was occuring up to 2500 or 3K RPM. Again, not shaking more roughly but just occuring now at higher RPM’s. Almost feeling as if you had dirty gas in your engine, this time loss of power was more noticeable. Since engine was now burning gas rapidly (maybe getting 50% normal mpg) after driving 1 hour on freeway so I went straight to the dealer.
Dealer did Dx scan and found engine code as misfire on cyliner 2. Was also told spark plugs were dirty and wires had high resistance. Tech recommended replace plugs/wires and do valve adjustment. I was dubious on the valve adjustment due to the high cost, so instructed dealer to have wires/plugs done.
Wires/plugs were replaced and dealer called back to say engine misfiring was worse and in fact now backfiring. I was told that valve adjustment would fix it as now it was certain it was loose or tight valves causing the issue. Tech explained that now due to better ignition from replaced wires/plugs, stronger misfire only indicated issues with the valves. I asked tech/dealer to verify wiring order to ensure they didn’t put it on wrong. Since I also had issues with my brakes and was up for 120K (30K interval) service I authorized and negotiatied a deal for the valve adjustment, 30K service, and brakes to all be done.
Next day dealer informs me after valve adjustment engine still misfiring on two. They now are saying they need to remove the engine head on cyl 2 side to do full valvetrain inspection. Now already $2K in to repairs they are asking for another $800 or so, saying valvetrain inspection and head removal costs 6.5 hours of tech time (shop labor rate $120/hr). They say it could be as easy as carbon on valve seat, chip in valve, bent valve etc - but could be as bad as chip/crack in head or internal crack. Was warned if could not be found via valvetrain inspection will have to go to machine shop to perform vacuum test to check for cylinder leaks etc.
I’m starting to get really suspicious. The original valve adjustment sounded funny to me, but I went along. After that I’m getting more suspicious as their quotes seem a bit high, and I don’t really buy the possiblities given I’ve treated this car so well and that the issues only seem to occur at less than 3K RPM. Thoughts? Is the dealer hosing me? Are they diagnosing this properly? What should I do?